DETECTION OF CHARGE SCATTERING ASSOCIATED WITH STRIPE ORDER IN LA1.775SR0.225NIO4 BY HARD-X-RAY DIFFRACTION

In the past few years neutron-scattering experiments have shown very i ntriguing stripe correlations of spins and holes in hole-doped La2NiO4 and La2CuO4. As yet, no x-ray-diffraction experiment has confirmed th e neutron results and the topic is still controversial. In this paper we report the observation of stripe correlations of holes by x-ray dif fraction. The experiments were performed in Laue geometry at the hard- x-ray beamline BW5 at HASYLAB on a crystal of La1.775Sr0.225NiO4 which was previously studied by neutron diffraction. Temperature dependence s of the intensities and wave vectors of the charge-density-modulation peaks were characterized and found to be in good agreement with the n eutron-scattering results. Interestingly, weak, temperature-dependent scattering was also observed at positions consistent with nonresonant x-ray magnetic scattering from the spin correlations; however, a defin itive determination of its origin remains lacking.